= 32,43 kJm
2
6. Menghitung Kekuatan Tarik sampel komposit
Nilai kekuatan tarik dapat dihitung dengan menggunakan persamaan berikut :
σ =
Dengan :
σ
= Kuat tarik Mpa F = Gaya N
A = Luas permukaan mm
2
a. Komposisi 0
Beban sampel = 23,84 kgf Tebal sampel
= 3 mm Lebar sampel = 20 mm
Sehingga : Luas A
= b x d = 20 mm x 3 mm
= 60 mm
2
Loadbeban P = 23,84 x 9,8 ms
2
= 233,63 N
σ =
=
,
= 3,9 MPa
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b. Komposisi 1
Beban sampel = 35,45 kgf Tebal sampel
= 3 mm Lebar sampel = 20 mm
Sehingga : Luas A
= b x d = 20 mm x 3 mm
= 60 mm
2
Loadbeban P = 35,45 kgf x 9,8 ms
2
= 347,41 N
σ = =
,
= 5,8 MPa
c. Komposisi 2
Beban sampel = 37,05 kgf Tebal sampel
= 3 mm Lebar sampel = 20 mm
Sehingga : Luas A
= b x d = 20 mm x 3 mm
= 60 mm
2
Loadbeban P = 37,05 kgf x 9,8 ms
2
= 363,09 N
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σ = =
,
= 6,05 MPa
d. Komposisi 3
Beban sampel = 63,93 kgf Tebal sampel
= 3 mm Lebar sampel = 20 mm
Sehingga : Luas A
= b x d = 20 mm x 3 mm
= 60 mm
2
Loadbeban P = 63,93 kgf x 9,8 ms
2
= 626,51 N
σ =
=
,
= 10,4 MPa
e. Komposisi 4
Beban sampel = 46,76 kgf Tebal sampel
= 3 mm Lebar sampel = 20 mm
Sehingga : Luas A
= b x d
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= 20 mm x 3 mm = 60 mm
2
Loadbeban P = 46,76 kgf x 9,8 ms
2
= 458,25 N
σ =
=
,
= 7,64 MPa
f. Komposisi 5
Beban sampel = 44,47 kgf Tebal sampel
= 3 mm Lebar sampel = 20 mm
Sehingga : Luas A
= b x d = 20 mm x 3 mm
= 60 mm
2
Loadbeban P = 44,47 kgf x 9,8 ms
2
= 435,81 N
σ =
=
,
= 7,3 MPa
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LAMPIRAN D STANDAR PEMBUATAN SAMPEL
ASTM D256
Significance and Use
Before proceeding with these test methods, reference should be made to the specification of the material being tested. Any test specimen preparation,
conditioning, dimensions, and testing parameters covered in the materials specification shall take precedence over those mentioned in these test methods. If
there is no material specification, then the default conditions apply.
The pendulum impact test indicates the energy to break standard test specimens of specified size under stipulated parameters of specimen mounting, notching, and
pendulum velocity-at-impact.
The energy lost by the pendulum during the breakage of the specimen is the sum of the following:
Energy to initiate fracture of the specimen; Energy to propagate the fracture across the specimen;
Energy to throw the free end or ends of the broken specimen “toss correction”; Energy to bend the specimen;
Energy to produce vibration in the pendulum arm; Energy to produce vibration or horizontal movement of the machine frame or
base;
Energy to overcome friction in the pendulum bearing and in the indicating mechanism, and to overcome windage pendulum air drag;
Energy to indent or deform plastically the specimen at the line of impact; and
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Energy to overcome the friction caused by the rubbing of the striker or other part of the pendulum over the face of the bent specimen.
For relatively brittle materials, for which fracture propagation energy is small in comparison with the fracture initiation energy, the indicated impact energy
absorbed is, for all practical purposes, the sum of factors 5.3.1 and 5.3.3. The toss correction see 5.3.3 may represent a very large fraction of the total energy
absorbed when testing relatively dense and brittle materials. Test Method C shall be used for materials that have an Izod impact resistance of less than 27 Jm 0.5
ft·lbfin.. See Appendix X4 for optional units. The toss correction obtained in Test Method C is only an approximation of the toss error, since the rotational and
rectilinear velocities may not be the same during the re-toss of the specimen as for the original toss, and because stored stresses in the specimen may have been
released as kinetic energy during the specimen fracture.
For tough, ductile, fiber filled, or cloth-laminated materials, the fracture propagation energy see 5.3.2 may be large compared to the fracture initiation
energy see 5.3.1. When testing these materials, factors see 5.3.2, 5.3.5, and 5.3.9 can become quite significant, even when the specimen is accurately
machined and positioned and the machine is in good condition with adequate capacity. See Note 7. Bending see 5.3.4 and indentation losses see 5.3.8 may
be appreciable when testing soft materials.
Note 7—Although the frame and base of the machine should be sufficiently rigid and massive to handle the energies of tough specimens without motion or
excessive vibration, the design must ensure that the center of percussion be at the center of strike. Locating the striker precisely at the center of percussion reduces
vibration of the pendulum arm when used with brittle specimens. However, some losses due to pendulum arm vibration, the amount varying with the design of the
pendulum, will occur with tough specimens, even when the striker is properly positioned.
In a well-designed machine of sufficient rigidity and mass, the losses due to factors 5.3.6 and 5.3.7 should be very small. Vibrational losses see 5.3.6 can be
quite large when wide specimens of tough materials are tested in machines of insufficient mass, not securely fastened to a heavy base.
With some materials, a critical width of specimen may be found below which specimens will appear ductile, as evidenced by considerable drawing or necking
down in the region behind the notch and by a relatively high-energy absorption, and above which they will appear brittle as evidenced by little or no drawing
down or necking and by a relatively low-energy absorption. Since these methods permit a variation in the width of the specimens, and since the width dictates, for
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many materials, whether a brittle, low-energy break or a ductile, high energy break will occur, it is necessary that the width be stated in the specification
covering that material and that the width be reported along with the impact resistance. In view of the preceding, one should not make comparisons between
data from specimens having widths that differ by more than a few mils.
The type of failure for each specimen shall be recorded as one of the four categories listed as follows:
1. Scope
Kategori